/**
 * Gps Service
 * 百度坐标偏离转换服务
 */

angular.module('JiangGanApp')
  .service('GpsService', GpsService);


function GpsService() {

  var pi = 3.14159265358979324;  
  var a = 6378245.0;  
  var ee = 0.00669342162296594323; 
  var x_pi = 3.14159265358979324 * 3000.0 / 180.0;  

  /** 
   * 地球坐标转换为火星坐标，即WGS84（国际通用）转为GCJ02坐标系
   * 适用于腾讯地图、高德（阿里）地图或谷歌地图 
   * @param gg_lat 
   * @param gg_lon 
   */  
  this.transform = function(wgLat, wgLon) { 
    var latlng = [];
    if (outOfChina(wgLat, wgLon)) {  
        latlng[0] = wgLat;  
        latlng[1] = wgLon;  
        return latlng;  
    }  
    var dLat = transformLat(wgLon - 105.0, wgLat - 35.0);  
    var dLon = transformLon(wgLon - 105.0, wgLat - 35.0);  
    var radLat = wgLat / 180.0 * pi;  
    var magic = Math.sin(radLat);  
    magic = 1 - ee * magic * magic;  
    var sqrtMagic = Math.sqrt(magic);  
    dLat = (dLat * 180.0) / ((a * (1 - ee)) / (magic * sqrtMagic) * pi);  
    dLon = (dLon * 180.0) / (a / sqrtMagic * Math.cos(radLat) * pi);  
    latlng[0] = wgLat + dLat;  
    latlng[1] = wgLon + dLon;  
    return latlng;
  };

  function outOfChina(lat, lon) {  
    if (lon < 72.004 || lon > 137.8347)  
      return true;  
    if (lat < 0.8293 || lat > 55.8271)  
      return true;  
    return false;  
  };

  function transformLat(x, y) {  
    var ret = -100.0 + 2.0 * x + 3.0 * y + 0.2 * y * y + 0.1 * x * y + 0.2 * Math.sqrt(Math.abs(x));  
    ret += (20.0 * Math.sin(6.0 * x * pi) + 20.0 * Math.sin(2.0 * x * pi)) * 2.0 / 3.0;  
    ret += (20.0 * Math.sin(y * pi) + 40.0 * Math.sin(y / 3.0 * pi)) * 2.0 / 3.0;  
    ret += (160.0 * Math.sin(y / 12.0 * pi) + 320 * Math.sin(y * pi / 30.0)) * 2.0 / 3.0;  
    return ret;  
  };

  function transformLon(x, y) {  
    var ret = 300.0 + x + 2.0 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * Math.sqrt(Math.abs(x));  
    ret += (20.0 * Math.sin(6.0 * x * pi) + 20.0 * Math.sin(2.0 * x * pi)) * 2.0 / 3.0;  
    ret += (20.0 * Math.sin(x * pi) + 40.0 * Math.sin(x / 3.0 * pi)) * 2.0 / 3.0;  
    ret += (150.0 * Math.sin(x / 12.0 * pi) + 300.0 * Math.sin(x / 30.0 * pi)) * 2.0 / 3.0;  
    return ret;  
  };

  /** 
   * 地球坐标转换为百度坐标，即GCJ02坐标系转为为BD09坐标系
   * 适用于百度地图 
   * @param gg_lat 
   * @param gg_lon 
   */  
  this.bd_encrypt = function(lat, lon){  
    var latlng = this.transform(lat,lon);
    var x = latlng[1], y = latlng[0];  
    var z = Math.sqrt(x * x + y * y) + 0.00002 * Math.sin(y * x_pi);  
    var theta = Math.atan2(y, x) + 0.000003 * Math.cos(x * x_pi); 
    latlng[0] = z * Math.sin(theta) + 0.006;  
    latlng[1] = z * Math.cos(theta) + 0.0065;  
    return latlng;
  }  

};
